HIGH-ANGLE ANNULAR DARK-FIELD IMAGING OF STACKING-FAULTS

High angle annular dark field imaging has been extensively applied to high resolution imaging of crystalline materials. Dislocations have al so been imaged using the high angle dark field detector, even when the lattice has not been directly resolved. Diffraction contrast, as empl oyed in transmission electron microscopy analysis of defects, is a pos sible mechanism for dislocation contrast. Stacking faults should also show diffraction contrast and a Bloch wave theory is developed for the high angle dark field image. The results are compared with an experim ent which shows, in agreement with the theory, that the strongest cont rast is found when the fault is close to the surface and the objective aperture is small. (C) 1997 Elsevier Science Ltd.